REPRODUCTIVE VARIATION AND THE EGG SIZE CLUTCH SIZE TRADEOFF WITHIN AND AMONG POPULATIONS OF PAINTED TURTLES (CHRYSEMYS-PICTA BELLII)

Intet-population variation in egg size, clutch size and clutch mass wa s studied 3 years in four populations of painted turtles (Chrysemys pi cta bellii) from western Nebraska. Body size varied among all populati ons and was larger in two large (56-110 ha), sandhills lake population s than in two populations in smaller habitats (1.5-3.6 ha) of the Plat te River floodplain. Reproductive parameters (egg mass, clutch mass, a nd clutch size) generally increased with maternal body size within pop ulations. Clutch wet and dry mass varied among populations but largely as a function of maternal body size. Clutch size was largest in the s andhills lake populations, both absolutely and relative to maternal bo dy size. Egg mass was smallest in the sandhills lakes and varied annua lly in one population. Over all populations, an egg size-clutch size t rade-off was detected (a negative correlation between egg mass and clu tch size) after statistically removing maternal body size effects. Egg wet mass and clutch size were negatively correlated over all years wi thin the sandhills populations and in some years in three populations. Although egg size varied within populations, egg size and clutch size covaried as expected by optimal offspring size models. Thus, patterns of egg size variation should be interpreted in the context of proxima te or adaptive maternal body size and temporal effects. Comparisons am ong populations suggest that large egg size relative to maternal body size may occur when juvenile growth potential is poor and mean materna l body size is small.